The invention relates to an internal combustion engine of the type wherein heat produced by the engine is transferred to a radiator by the circulation of coolant from coolant lines and spaces in the engine to the radiator via a pair of coolant transport lines.
Internal combustion engines have always been air- or water-cooled, today mainly water-cooled.
With air-cooling, the heat that is genrated during combustion and transferred to the cylinder head and the cylinder block of the engine block is eliminated by blowing cool air on these parts. In doing so, the air heats up correspondingly. The surface of the engine parts to be cooled is enlarged by fins to facilitate heat extraction. An air-cooled interanl combustion engine reaches its operating temperature relatively quickly, but this temperature is higher than the operating temperature of water-cooled internal combustion engines and the cooling is also more uneven than with water.
With a water-cooled internal combustion engine, the cylinder head and the cylinder block are constructed with double walls, and in the spaces so created, a water/antifreeze mixture flows as a coolant from the bottom upward. The heated coolant leaves the engine block at the highest point and flows through an air radiator in which the coolant flows from the top downward through a large number of channels placed parallel to each other. The coolant cooled in the radiator is again fed to the engine block at the lowest point and distributed throughout the system of coolant lines and spaces in the engine block. So that a cold internal combustion engine can reach its operating termperature quickly, the system of coolant lines and spaces can be closed in an inner loop within which only a small amount of coolant circulates until the operating temperature of the engine block has been reached, and then, a thermostat switch opens a large loop to the radiator. Despite this, because a water-cooled system contains a relatively large amount of coolant with a correspondingly high heat absorption capacity, a water-cooled internal combustion engine takes a relatively long time for the operating temperature to be reached. During this warm-up phase, the wear to which the internal combustion engine is sugjected is considerable, and until the operating temperature is reached, there are superproportionally high amounts of pollutants in the exhaust gas. Futher, the structual expense for conveying the water with a pump, thermostat, hose lines, radiator core, etc., is not unsubstantial. Finally, with the usual coolant of a water/antifreeze mixture, reaching temperatures over 100.degree. C. is connected with quite a considerable additional expense, since then the cooling system must be made pressure resistant. Operating temperatures of the internal combustion engine over 100.degree. C., which would generally be suitable for efficiency, can thus hardly be reached with water-cooled internal combustion engines.